Dental restorative materials include materials used to repair damaged teeth and/or replace missing teeth and/or other related oral structures. In some instances, dental restorative materials include materials used to reconstruct the maxillofacial complex. In general, dental restorative compositions include: (1) fillers, (2) binders, (3) dental amalgam, (4) enamel and dentin bonding agents, (5) dental composites, (6) dental cements, (7) casting alloys for crowns and bridges, (8) ceramic/metal materials, (9) denture and prosthetic materials, (10) porcelains, and (11) ceramic restorative materials, etc..
A variety of compositions have been proposed and used for the direct filling of teeth. Of these compositions, some may be generally classified as dental composites and more specifically as resin composites. These resin composites are comprised of inorganic particulates, i.e., filler, bound together with a polymeric matrix, i.e., a binder. The particulate filler reinforces the polymeric matrix and offsets its deficiencies. The binder, and/or polymeric matrix, may be comprised of an acrylic or epoxy resin or other types of carbon-based polymers. See, for example, U.S. Pat. Nos. 3,066,112 and 3,179,623 which are hereby incorporated by reference. Fillers for such composite compositions, both posterior and/or anterior dental use, include finely divided solids like silica, glass, zirconium, aluminum oxide, crystalline quartz, glass beads, or a mixture of glass beads and quartz. A material acceptable, however, for posterior use must be able to achieve a high filler loading capacity in the resin system. Moreover, filler strength, content, shape and size directly determines the physical and mechanical properties of the restoration material.
To date, there has been no composite material developed that completely meets the expected parameters needed for the intended use as a posterior dental restorative material to replace mercury-based dental amalgams. Dental materials presently available lack several physical or mechanical properties necessary for an ideal posterior dental restoration. As noted, it is imperative to achieve a high filler loading capacity in the resin system and presently all attempts to achieve such have failed. For example, highly loaded materials such as Microfine Composite.TM., using colloidal silica of a 40 nm size result in dramatically increased viscosity which jeopardizes handling characteristics. (See, Lambrechts, P; Vanherle, G. (I1983); Structural Evidence of Microfilled Composites. J. Biomed Mater Res 17: 249-60.; Willems, G; Lambrechts, P.; Braen, M.; Celis, J. P.; Vanherle, G. (1993): A Classification of Dental Composites according to their Morphology and Mechanical Characteristics. Dent Mater 8: 310-19). The colloidal silica forms an extended network structure that produces an increase in viscosity thereby limiting the amount of filler that can be incorporated to around 50% by volume. This 50% volume of filler loading has only been obtained by first filling to higher degree, that is, greater than 50% during manufacturing, and then curing under high temperature and grinding to make colloidal oxide field resin particles (organic fillers). However, a major problem still remains. The interface between these particles and the matrix, i.e., binder, is weak and causes brittle failure and wear. The filler composition of the present invention has the characteristics needed for posterior composite materials when combined with a resin matrix to address and solve these major hurtles.
The properties needed for an advantageous dental restorative material include, inter alia, the following: (1) low to high density, (2) high tensile/compression strength (3) low thermal conductivity, (4) purity, (5) long life in cyclic applications, (6) high flexural strength, (7) rigidity, (8) inertness, (9) dimensional stability, (10) thermal shock resistance, (11) high diffusitivity, and (12) porosity. The present invention provides heretofore unknown fused-fibrous dental restorative materials with the above properties.